Many theories attempting to explain what happened to him were put forward over the years; in 2018 new claims regarding his disappearance were made by Israeli journalist and author Ronen Bergman in his book Rise And Kill First: The Secret History of Israel's Targeted Assassinations.
[citation needed] His outstanding academic performance attracted the attention of the French Résident Général Charles Noguès, who sent him along with other distinguished students on a trip to Paris.
[11] He also remained an activist in the nationalist movement, to the extent that the French General Alphonse Juin described him as the "enemy #1 of France in Morocco.” Mehdi Ben Barka was put under house arrest in February 1951.
[12] Around this time, Ben Barka increasingly embraced revolutionary Marxist language, and the UNFP adopted a political program based on socialism and land reform, aiming to democratize public life and align the party with anti-imperialist Arab and African countries.
[citation needed] Chairing the preparatory commission, he defined the objectives; assistance with the movements of liberation, support for Cuba during its subjection to the United States embargo, the liquidation of foreign military bases and apartheid in South Africa.
According to Tad Szulc, Israeli involvement was in the wake of the successful Moroccan-Israeli collaboration in the 1961–64 Operation Yachin; he claims that Meir Amit located Ben Barka, whereupon Mossad agents persuaded him to come to Paris where he was to be arrested by the French police.
[16] In the 1960s Ben Barka's disappearance was enough of a scandale public that President De Gaulle, who ordered an investigation, formally declared that the French police and secret service had not been responsible.
[17] Georges Figon, a freelance barbouze (secret agent)[18] who had testified earlier that Oufkir stabbed Ben Barka to death, was later found dead, officially a suicide.
[citation needed] Prefect of Police Maurice Papon (1910–2007), later convicted of crimes against humanity for his role under the Vichy regime, was forced to resign following Ben Barka's kidnapping.
[citation needed] A former member of the Moroccan secret service, Ahmed Boukhari claimed in 2001 that Ben Barka had died during interrogation in a villa south of Paris.
Furthermore, he declared that this vat of acid, whose plans were reproduced by the newspapers, had been constructed under instructions from the CIA agent "Colonel Martin", who had learnt this technique to make corpses disappear during his appointment in the Shah's Iran in the 1950s.
However, the son of Mehdi Ben Barka was outraged at what he called a "pseudo-release of files", insisting that information had been withheld which could have implicated the French secret services (SDECE), and possibly the CIA and the Mossad, as well as the ultimate responsibility of King Hassan II of Morocco–who conveniently was able to put the blame on Oufkir after his failed coup in 1972.
[20] Driss Basri, Interior Minister of Hassan II and his right-hand man from the early 1980s to the late 1990s, was heard by the judge Patrick Ramaël in May 2006, as a witness, concerning Ben Barka's kidnapping.
[23] But just one day after the Mossad had received the transcripts from this Arab summit, a top Moroccan intelligence service chief, Ahmed Dlimi requested - on behalf of King Hassan II - that the Israelis immediately repay the favor by assassinating Ben Barka.
"The Mossad supplied the Moroccans with safe houses in Paris, vehicles, fake passports, and two different kinds of poison with which to kill [Barka], as well as shovels and 'something to disguise the traces'".
During his last visit in Prague in early October 1965, Mehdi Ben Barka complained that King Hassan II was taking various measures against him and asked the secret service for a small handgun to protect himself as he feared assassination.
[25] Victoria Brittain, writing in The Guardian, called Ben Barka a "revolutionary theoretician as significant as Frantz Fanon and Che Guevara", whose "influence reverberated far beyond their own continent".